last week, samsung unveiled its galaxy s4. >>> apple stepping up its mar t marketing against samsung. 12 reasons why the iphone is better. you have to imagine the timing suggesting the message is geared towards samsung's new galaxy s4, which was unveiled last week. >>> for the first time ever, congress holding a hearing surrounding threats coming from outer space. they're concerned asteroids and meteors, not only pose a danger to earth but also to orbiting satellites. the house committee will track the space threats. and the committee will discuss ways to deal with any threats that happen to be discovered. >> just to be safe, walk around with a big helmet on. >> the sky is falling. >>> 6:26 right now. >>> still ahead, a call to service for catholics. and the pope answers that call. >>> we're going to take you live to vatican city, as the pope delivers his greatest hope for the catholic church. >>> and details in a tragedy at the racetrack. what may have happened inside a teenager's race car just moments before he struck and killed his young cousin. >>> we're also keeping tabs on the f